In recent years, large cars have employed a multistage transmission having the number of gear stages such as 12 stages and 16 stages. In such multistage transmission, there is employed a method in which not only the gear stage is increased to be made multi-staged, but is made multi-staged by the combination of an auxiliary transmission and a main transmission, which is called a splitter or a range. There are examples, not only in large cars but also in passenger cars, where an 8-speed transmission of 2×4 or 10-speed transmission of 2×5 is employed.
However, in a gear shifting operation device of the multistage transmission in which the auxiliary transmission is provided to be made multi-staged, a gear stage of the auxiliary transmission must also be changed simultaneously when a gear stage of the main transmission is changed, and a structure of the gear shifting operation device becomes complex.
Here, a conventional gear shifting operation device of a multistage transmission will be explained with reference to FIG. 8. It should be noted that here, there is exemplified a structure of a gear shifting operation device of 8-speed transmission of 2×4 as one example. A multistage transmission 2 includes a main transmission 3 and an auxiliary transmission 4, a main shaft 5 is provided with gear stages G1, G2, G3, and G4, and a sub-shaft 6 is provided with gear stages GH and GL. These gear stages are combinations of each counter gear with which counter shafts not shown are provided, and shift gears with which the main shaft 5 and the sub-shaft 6 are provided. In addition to this, the multistage transmission 2 is provided with coupling sleeves S1 to S3 and shift forks F1 to F3 which cause each gear to synchronize with the main shaft 5 or the sub-shaft 6.
In this multistage transmission 2, a first-speed stage is set as a combination of the gear stage G1 of the main transmission 3 and the gear stage GL of the auxiliary transmission 4, and the subsequent speed stages can be set as the following combinations sequentially from the first-speed stage: a second-speed stage is as the gear stage G2 and the gear stage GL; a third-speed stage is as the gear stage G3 and the gear stage GL; a fourth-speed stage is as the gear stage G4 and the gear stage GL; a fifth-speed stage is as the gear stage G1 and the gear stage GH; a sixth-speed stage is as the gear stage G2 and the gear stage GH; a seventh-speed stage is as the gear stage G3 and the gear stage GH; and an eighth-speed stage is as the gear stage G4 and the gear stage GH.
In this multistage transmission 2, the shift forks F1 to F3 oscillate, and the coupling sleeves S1 to S3 move on the main shaft 5 or the sub-shaft 6 in an axial direction thereof by the oscillation. The coupling sleeves S1 to S3 are then synchronously coupled to each gear stage, and thereby a gear is shifted.
A gear shifting operation device 1X is provided with: a shift mechanism 10X for main transmission; a shift mechanism 30X for auxiliary transmission; a select mechanism 40X for main transmission; an operation portion 50X for main transmission; a shift pattern 60X for main transmission; an operation portion 70X for auxiliary transmission; and a shift pattern 80X for auxiliary transmission.
Next, a gear shifting method of the multistage transmission 2 will be explained. First, the operation portion 70X for auxiliary transmission is operated, the shift mechanism 30X for auxiliary transmission is caused to operate, the shift fork F3 is oscillated, and the coupling sleeve S3 is synchronously coupled to the gear stage GL or the gear stage GH. Next, select operation of the operation portion 50X for main transmission is performed, the select mechanism 40X is caused to operate, and the shift fork F1 or F2 is operatively selected. Next, shift operation of the operation portion 50X for main transmission is performed, the shift mechanism 10X for main transmission is caused to operate, the selected shift fork F1 or F2 is oscillated, and the coupling sleeve S1 or S2 is synchronously coupled to each of the gear stages G1 to G4.
When the gear in the multistage transmission 2 a is shifted as described above, the operation portion 70X for auxiliary transmission for operating the auxiliary transmission 4 and the operation portion 50X for main transmission for operating the main transmission 3 are needed, and operation becomes very complicated. In addition, since the gear is shifted by using two operation portions, it becomes difficult to comprehend which gear stage is selected.
As measures against the above, there are a device and the like which are provided with a switch with which an auxiliary transmission can be operated, at a shift lever of an operation portion for main transmission, and in which, with the use of the switch, a shift mechanism for auxiliary transmission is operated by electronic control. Although operation can be performed by one operation portion in this device, operation of the main transmission and operation of the auxiliary transmission are divided also in the device, and complexity of the operation cannot be eliminated.
In relation to this, there is a range-type multistage transmission in which operation of a main transmission and an auxiliary transmission is performed by one shift lever (for example, refer to Patent Document 1). This device is the one that detects operation of a shift fork of the main transmission, and actuates, by a driving device, the shift fork that switches shift gears of the auxiliary transmission.
Also other than the device, a multistage transmission in which a gear stage of an auxiliary transmission is operated by a driving device, such as an electronically controlled actuator, is put into practical use. However, there have been problems of complicated electronic control, not being able to select an arbitrary gear stage, or the like.